JPS5933299B2 - Polyphenylene sulfide painted body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a painted body using polyphenylene sulfide as a paint.It can be used as a rust-proofing and corrosion-proofing material for metal surfaces by utilizing the excellent heat resistance, chemical resistance, etc. of polyphenylene sulfide resin. The use of these resins has been rapidly increasing in recent years, and these resins have come to be frequently used as paints for metal surfaces.

However, the inventors of the present invention found that the coating film of this resin surprisingly has high water permeability to hot water, and that it becomes a relatively flexible coating film at high temperatures. We discovered that when exposed to hot water for a long period of time, the adhesion to metal deteriorates, and furthermore, blistering occurs, which impairs the function of the coating film.We decided to solve this problem. The present invention was achieved as a result of intensive study of the purpose.

That is, the gist of the present invention resides in a polyphenylene sulfide coated body, which is characterized in that a polyphenylene sulfide coating is formed on a metal surface, and the coating has a multilayer structure including a foam layer.

In the present invention, polyphenylene sulfide resin, which has been conventionally provided for coating purposes, can be used.
It is preferable that the resin has relatively poor flow, and 3
Melt flow under 5kg load at 20℃ is 60~10
00fl/10 minutes, particularly preferably 60 to 300y/10 minutes.

The coated body of the present invention has a multilayer polyphenylene sulfide coating film including a foam layer formed on a metal surface, and it is preferable that the foam layer is sandwiched between non-foam layers. For example, when the coating film has a three-layer structure, it is preferable that the coating layer provided in contact with the metal surface is a non-foamed layer, the intermediate layer is a foamed layer, and the outermost layer is a non-foamed layer. Further, it is preferable that the non-foamed layer is a coating layer consisting solely of polyphenylene sulfide resin. Further, to form a foam layer, a suitable foaming agent capable of foaming the polyphenylene sulfide resin when heated is blended with the polyphenylene sulfide resin, this mixture is coated, and foaming is performed by heating. J Suitable blowing agents used in the present invention include organometallic compounds that decompose or react under heating at temperatures below 290°C and release gas, such as metal salts of organic carboxylic acids, adsorbed water, or water of crystallization. Examples include inorganic compounds that contain water and release water at a temperature of 100°C or higher and 290°C or lower.

-c As a typical example of this inorganic compound, Ca
Cl2・1~6H20,,CaS()4・2H2O
, , Ca(NO3)2.16H20 and the like. However, regarding the amount of these blowing agents added, if it is too large, the bubbles will become coarse and the coating performance will deteriorate. It is preferable to add 0.2 to 2 parts by weight, especially 0.2 to 2 parts by weight.

To manufacture the coated body of the present invention, a foamable polyphenylene sulfide paint and a non-foamable polyphenylene sulfide paint containing a foaming agent as described above are prepared, and these paints are mixed with the above foamable paint. This can be carried out by applying a multilayer structure containing a coating film according to a conventional method, and baking the foamable coating layer by heating the coating after coating, and foaming the foamable coating layer at the same time. Preferably, the foamable coating layer is sandwiched between non-foaming coating layers. for example,
A metal plate is heated to 285°C or higher in advance, and a powder of polyphenylene sulfide resin is applied to it. After a uniform coating is formed, a resin mixture mixed with a foaming agent is applied. Powder of polyphenylene sulfide resin is coated on top of it to form a three-layered coating film, which is then cooled, and then heated to a temperature of 350 to 450°C for 10 minutes to several hours. A painted body in which a foam layer is formed on the edges is obtained. The reason why the coated body of the present invention has excellent heat resistance, chemical resistance, etc. as well as hot water resistance is not clear in detail, but due to some reason based on the multilayer structure of the coating film, the coating film is not easily penetrated by hot water. It is presumed that the permeation of the metal into the metal interface is suppressed, and as a result, a decrease in interfacial adhesion is prevented, making it extremely difficult for the pristine phenomenon to occur.

Since the polyphenylene sulfide coated body of the present invention has the above-mentioned structure, in addition to the excellent properties of the conventional polyphenylene sulfide coated body, it also has improved hot water resistance. In particular, it can be applied to areas or applications that come into contact with hot water for a long period of time, such as the inner surface coating of hot water or steel pipes for hot water, and can produce excellent effects.

Examples of the present invention will be described below. Examples 1 and 2 and Comparative Example 1 One side of an iron plate of 10CIn1 thickness 3m711 both vertically and horizontally was sandblasted and preheated to 38''C in an electric furnace.

A paint containing polyphenylene sulfide resin alone, a paint having the composition shown in Table 1, and a paint containing polyphenylene sulfide resin alone were applied to this in this order to a thickness of approximately 130μ each, and the total thickness was was set to about 400μ. Further, in a comparative example, a paint made of polyphenylene sulfide resin alone was applied to a thickness of about 400 μm. The thus coated iron plate was heat-treated at 38°C (30 minutes) and then put into water for rapid cooling. Due to this heating, the second layer of the coating foamed and the entire coating layer was heated. The thickness is about 65
It had increased to 0μ. The sample piece prepared in this way was attached to a container-shaped lining tester so that the painted side was in contact with the hot water and the other side was in contact with the outside air, and the sample piece was heated to 95°C ± 5°C.
Hot water maintained at ℃ was added and left to stand for a long period of time, and the time required for pristal formation to form on the painted surface was measured. The result is the first
It was as shown in the table. Note that the temperature difference between the side of the sample piece in contact with hot water and the outside air side was about 10°C.

In addition, the peel strength values in Table 1 are 905 for sample pieces exposed to hot water for 500 hours using the above lining tester.
It was determined by a peel test.

Claims (1)

[Scope of Claims] 1. A polyphenylene sulfide coated body, characterized in that a polyphenylene sulfide coating is formed on a metal surface, and the coating has a multilayer structure including a foam layer. 2 The coating film has a three-layer structure, the first layer in contact with the metal surface and the third outermost layer are both non-foaming coating films, and the first layer is a non-foaming coating film.
2. The coated body according to claim 1, wherein the second layer sandwiched between the layers and the third layer is a foamed coating film.